Inter-laboratory Comparisons (ILC) Detailed Information (Calibration Laboratories)

Transcription

1 National Laboratory Association Association Incorporated under Section 21 Not for Gain) P.O. Box 298 Persequor Park Pretoria, South Africa, 0020 Reg. No: 1994/002856/08 Tel: (+27) Fax: (+27) De Havilland Crescent Persequor Technopark Inter-laboratory Comparisons (ILC) Detailed Information (Calibration Laboratories) NLA-ILC-I Page 1 of 6

2 Contents Page 1. Introduction Page 3 2. Background Page 3 3. Benefits of participating in NLA run ILC Schemes Page 4 4. How are the NLA ILC Schemes run? Page 4 5. What Schemes are on offer and what costs are involved? Page 4 6. How do I participate? Page 4 7. How and when will I receive my results? Page 5 8. Amendment Record Page 6 NLA-ILC-I Page 2 of 6

3 1. Introduction The Inter-laboratory Comparison Schemes (ILCs), offered by the NLA, are specifically applicable to the calibration laboratory community. The ILCs make use of artefacts, which have been calibrated by a SANAS accredited Reference Laboratory, (typically the National Metrology Institute of South Africa), who have the smallest measurement uncertainties in the country. Participating laboratories pay a nominal fee to the NLA in order to participate which includes the provision of the artefact, the processing of the measurement results, calculation of the Normalised Error (En) value, and the issuing of a report. 2. Background The calibration laboratory community has become accustomed to participation in an annual SANAS audit programme at no additional cost. The big disadvantage of this programme is that it only audits a very limited scope of the laboratory technical capability and the delay in getting the results reported to the participating laboratory mean that they may continue to perform calibrations, blissfully unaware that the measurement results they are reporting, may be erroneous. It should be noted that the NLA ILC schemes are not designed to be in competition with the SANAS annual audit sample programmes, but are rather designed to compliment the SANAS programmes by auditing different technical areas. Since the inception of ISO/IEC 17025: 2005 and SANAS R-48, calibration laboratories have been obliged to participate in ILC activity to cover their entire scope of technical capability at least once every 5 years, or in line with the perceived risk. Unfortunately however, this has proven problematic for the following reasons:- - Finding willing participants to cover the required technical range has proven difficult, - In many cases, the measurement uncertainties of the selected participants have not been appropriate, - Reports, including calculated Normalised Error (En) values together with conclusions as to whether the ILC was satisfactory or whether corrective actions are required and their description, have not been generated. - Often, only bilateral ILCs take place and this increases the risk of producing perceived good results, when in fact both participants are not good but just equally bad. - The amount of time and effort required to organize and participate in suitable ILC activity has been grossly under-estimated. It could therefore be argued that whilst in most cases, there is no direct cost to the participants of these informal ILCs, the indirect costs to the participants remain unknown and can be significant. - Most of the ILCs are organized informally which typically results in informal records being generated, which do not meet the requirements of ISO/IEC 17025, or SANAS R-48. NLA-ILC-I Page 3 of 6

4 3. Benefits of participating in NLA run ILC Schemes. - The NLA offers several ILC Schemes, thereby covering a wide range of technical measurement capability. This enables calibration laboratories to select schemes to cover the widest possible range of measurement capability. - The ILC artefacts are instruments which are typical of those seen by calibration laboratories on a daily basis. They therefore realistically evaluate the competence of the laboratory to calibrate similar instruments received from customers for calibration. - The measurement uncertainties associated with the NLA ILC Scheme reference values is small thereby enabling most laboratories to be able to use their ILC scheme results to justify their accredited measurement capabilities. - The interim and consolidated reports issued to NLA ILC Scheme participants contain all the information required to fulfil the requirements of ISO/IEC as well as SANAS R How are the NLA ILC Schemes run? 4.1 These schemes are of an open ended nature meaning they have no defined start or completion date. Laboratories can elect to participate at any time provided the artefact is available. 4.2 Typically a laboratory wanting to participate identifies the particular scheme, registers to participate and books a tentative 1 week time slot. This slot is only confirmed upon receipt of the payment of the required fee. 4.3 Once the laboratory has performed the measurements, they return the artefact, and submit their measurement results to the NLA. 4.4 Within two weeks, an interim report will be issued indicating the laboratory s Normalized Error (En) values. A consolidated report will be issued at least annually, containing the results from all the participant laboratories, and this will usually be presented at the annual NLA Test & Measurement Conference. 5. What Schemes are on offer and what costs are involved? 5.1 Refer to the document NLA-PT-I PT and ILC Schemes Offering Summary. 6. How do I participate? 6.1 Refer to the document NLA-PT-I Proficiency Scheme Process Flow Chart. NLA-ILC-I Page 4 of 6

5 7. How and when will I receive my results? 7.1 Interim reports are ed to participants within two weeks of scheme participation. These reports will contain the absolute normalized error (En) values where an En value < 1 indicates satisfactory performance and an En value 1 indicates that corrective action is required. The report will also highlight potential problems. NLA-ILC-I Page 5 of 6

6 Amendment Record Revision Subject of Change Date 01 New Document 2011/07/08 NLA-ILC-I Page 6 of 6